Up to now, a twin-clutch type transmission has been provided, having a first input shaft X1 connecting to a first clutch D1, a second input shaft X2, inserted in said first input shaft X1, connecting to a second clutch D2, an output shaft Xo, and an idle shaft XR, wherein the 2nd, 4th and 6th speed drive gears G18, G19, G20 are fixedly carried on said first input shaft X1, the 1st, 3rd, 5th and reverse drive gear G21, G22, G23, G24 are fixedly carried on said second input shaft X2, and the 2nd, 4th, and 6th driven gears G25, G26, G27 respectively engaging with said three gears G18, G19, G20 of said first input shaft are rotatably carried on said output shaft Xo, further, the 1st, 3rd, 5th driven gears G28, G29, G30 engaging with said three gears G21, G22, G23 of said second input shaft X2 are rotatably carried on said output shaft Xo, furthermore, a reverse driven gear G32 connecting to said gear G24 of said second input shaft through a gear G31 is rotatably carried on said output shaft Xo, said gear G31 being rotatably carried on said idle shaft XR, still further, a output gear G12 connecting to a differential gear (4) is fixedly carried on said output shaft Xo, and coupling C5, C6, C7, C8 are respectively attached to said seven gears G25, G26, G27, G28, G29, G30, G32 to fix selectively to said output-shaft Xo, and said output gear G12 of said output shaft Xo is arranged in the clutch-most side.
In said transmission, a side space SP of said output gear G12 of said output shaft Xo is not especially utilized.
Nevertheless, in said conventional transmission (1), to ensure adequate space in which a plural number of gears corresponding to the numbers of speed stage changes are arranged, the lengths of said second input shaft X2 and said output shaft Xo should be expanded, so that the size of the shaft direction of said transmission (1) is too large, resulting in a troublesome installation procedure. In the case of the twin-clutch type transmission (1), especially in the case of a front wheel drive system where the engine is installed sideways, narrowing the transmission installation space, it is difficult to accommodate required shaft length.